What do the following two equations represent? $-5x+5y = 5$ $-20x-20y = -5$
Answer: Putting the first equation in $y = mx + b$ form gives: $-5x+5y = 5$ $5y = 5x+5$ $y = 1x + 1$ Putting the second equation in $y = mx + b$ form gives: $-20x-20y = -5$ $-20y = 20x-5$ $y = -1x + \dfrac{1}{4}$ The slopes are negative inverses of each other, so the lines are perpendicular.